MarsMars

Now: ~ opposition (rises when?) magnitude -2.2

Popular InterestPopular Interest

Past Past and and

presentpresent…… 1938: Radio 1938: Radio

broadcast broadcast of War of of War of the Worlds the Worlds panics USpanics US

2000: “Red 2000: “Red Planet”Planet”

2005 (and 2005 (and 1953) “War 1953) “War of the of the Worlds”Worlds”

First First ObservationsObservations

First observed by Dutch physicist Christian Huygens, 1659

He noted…

RotationRotation

Motion of the feature Syrtis Major and concluded P=24h

Giovanni Cassini

Determined to be 24:37 who also saw the polar caps…

Polar Ice CapsPolar Ice Caps

Ice cap Ice cap seen in seen in this this ground ground based based photophoto

Similar to Similar to view in view in scopescope

Seasons and eccentricity Seasons and eccentricity

Seasons are affected (made more extreme) because perihelion occurs at Southern Hemisphere summer

This is unlike Earth seasons, since Earth’s orbital This is unlike Earth seasons, since Earth’s orbital eccentricity is smalleccentricity is small

Eccentricity and Eccentricity and OppositionsOppositions

Causes Causes some some oppositions oppositions to be to be “favorable”“favorable”

September September 2003’s was 2003’s was especially especially favorablefavorable

Note angular Note angular size of Marssize of Mars

Giovanni Schiaparelli First proposed that First proposed that

the caps made of the caps made of iceice

Became famous Became famous when he drew his when he drew his sketch of Mars in sketch of Mars in 1877 …1877 …

““Canali” (Canali” (channels/canals)

Percival LowellPercival Lowell

Wealth “Boston Wealth “Boston Brahman” (social Brahman” (social and cultural elite)and cultural elite)

Became Became interested in the interested in the Mars canals and Mars canals and established an established an observatory in observatory in Flagstaff, AZFlagstaff, AZ

Lowell at the scopeLowell at the scope Drew on 6-inch globes Drew on 6-inch globes

to accommodate to accommodate perspectiveperspective

Edward Barnard

In 1894 Edward Barnard and others could not convince himself the canals existed

Mariner probes would resolveMariner probes would resolve

dust storm here frustrated first photos in 1971 Mariner 9

When cleared…When cleared…

Many features Many features but none lined but none lined up with canals up with canals drawn by drawn by Schiaparelli or Schiaparelli or LowellLowell

Possible explanation Possible explanation based on Lowell’s Venus based on Lowell’s Venus

“spokes”“spokes” Doctors noted that Doctors noted that

Lowell had Lowell had stopped his scope stopped his scope down to a few down to a few inches, effectively inches, effectively creating a pinhole creating a pinhole camera at eye, camera at eye, which displays which displays veins in retinaveins in retina

Similar to Similar to ophthalmoscope, ophthalmoscope, an instrument an instrument used to used to examine the examine the interior of the eye interior of the eye

Craters discovered

Not evenly distributed…Not evenly distributed…

Mostly in southern hemisphere

Dust has eroded rays and ejecta

Volcanoes found

Volcanoes such as Arsia Mons shown above and...

.. In perspective 3D

The volcano Olympus Mons

rises 24 km (15 miles) above plains! (3x Mt Everest). Great size of volcanoes on both Venus and Mars suggests no

current plate tectonics ... same surface sits above hot spot.

Tharsis Rise

Olympus Mons and other volcanos comprise the Tharsis Rise

Shown compared to eastern US here

Is an average of 5 - 6 km above most of surface

Valley Marineris

4000 km long

Would span USA as shown

It is a huge crust fracture

not formed by water, but…

These channels were formed by massive water

flow

But where is the water But where is the water now?...now?...

Some water locked up in polar ice caps

South pole shown here During summer CO2 portion sublimates, leaving

H2O. (Temperature rises above sublimation point)

color view of cap

shows ice melted off of sun-facing slopes, revealing strange terraced slopes

North pole

this is almost all residual water ice shown here

Broken terrain from outflow

in the Capri plateau, suggests water violently outgassed when heated by volcanic activity below

Like similar event in eastern Washington state 14,000 years ago that created the Channeled Scablands

Some water seen in fogSome water seen in fog

Early morning fog in canyons

1975-6: Two Viking Landers1975-6: Two Viking Landers

Approaching MarsApproaching Mars

dawn view reveals clouds along volcano Olympus Mons, Valley Marineris

CO2 snow in Argyre Basin

Viking I Lander View

Landed in Chryse Planitia (Golden Plains)

Shows edge of crater on horizon, probably responsible for jagged rocks in scene.

Foreground shows regolith covered with other rocks that under closer examination ...

… …appear pocked (vesicular)

Suggests outgassing during igneous formation

Weather Report from marsWeather Report from mars

Other ResultsOther Results

95% CO2, 2% N2, 1.6% Argon 6-8 mBar pressure (Earth: 1000 mB) no ozone layer no magnetic field (therefore no iron core,

also supported by low avg density 3.9) large temp swings ... -80OC to -20O C in

warmer areas! seasonal pressure variationss as CO2

freezes out/sublimates

Scoop Delivered Soil to Scoop Delivered Soil to ExperimentsExperiments

Geological ResultsGeological Results

surface rich in iron (magnet) --> rust red!

silicon --> 2/3 of Mars.. little interior info since one

seismometer failed...

Biological…

gas-exchange

Sensed respiration of samples (used gas-chromatograph/mass spectrometer)

labeled release

Used radioactive carbon nutrients -- checked for metabolism...

pyrolytic-release

Checked for photosynthesis with radioactive CO2 and artificial sunlight

Biological ResultsBiological Results

no life found active chemical reactions believed

due to release of peroxides & superoxides

surface is literally antiseptic!

MagnetosphereMagnetosphere

almost no magnetic field Thus, core, if iron, not liquid, since Prot ~ PEarth Thus solar wind and cosmic rays hit surface

July 1997: PathfinderJuly 1997: Pathfinder

Mars Global Surveyor

Imaging Mars from an orbit around itImaging Mars from an orbit around it Recent image of delta-like fansRecent image of delta-like fans